1. Field of the Invention
The invention concerns a high-pressure atomizing nozzle, including a nozzle body in which is formed a turbulence chamber, which is connected to an external space via at least one nozzle orifice and which has at least one supply duct for the fluid to be atomized, through which supply duct the fluid mentioned can be supplied under pressure.
The invention makes reference to a state of the art which is given under the title "Zerstauberbrenner (atomizer burner)" in the book "LUEGER--LEXIKON DER ENERGIETECHNIK UND KRAFTMASCHINEN", DVA Stuttgart 1965, p. 600.
2. Discussion of Background
In atomizer burners, the oil provided for combustion is mechanically finely distributed, i.e. it is broken down into small droplets of some 10 to 400 micron diameter (oil mist). The droplets, mixed with combustion air, evaporate and burn in the flame. In addition to atomizer types such as injection and swirl atomizers, so-called pressure atomizers are used. In these, oil is supplied under high pressure by a delivery pump to an atomizer nozzle which is fastened to a nozzle body. The oil enters a swirl chamber in substantially tangentially extending slots or ducts and leaves the nozzle via a nozzle orifice. The tangential inlet flow has the effect that the oil particles are given two components of motion, one azimuthal and one axial. The rotation of the fluid in the swirl chamber causes the formation of an air funnel whose apex extends into the swirl chamber. The oil film emerging from the nozzle orifice as a rotating hollow cylinder expands, because of the centrifugal force, into a hollow cone whose edges become subject to unstable vibration and break up into small oil droplets. The atomized oil forms a cone with a larger or smaller included angle.
The low-emission combustion of mineral fuels in modern burners places particular requirements on the atomization; these may be stated as follows:
the droplets must be very small so that they can evaporate before combustion; PA1 the included angle (angle of spread) of the oil mist should be small in certain types of burners, particularly in the case of combustion under high pressure (e.g. diesel engine, gas turbine); PA1 the droplets must have a very high velocity so that they can penetrate far enough into the combustion air stream (even when density is increased by a factor of 5 in, for example, a gas turbine combustion chamber).
Swirl nozzles of known design are less suitable for this purpose because they do not permit small angles of spread.